Engineer&#39;s protractor



June 14, 1927. 1,632,613

D: C. LOPEZ ENGINEERS PHOTRACTOR Fiied Deo. 1o. 1925 UNIT Patented June 14, `1.927.

,navln CABRERA LOPEZ, or CHICAGO, ILLINOIS,

PATENT IIGINEERs PBOTRACIQR.

i 1 .Appncatiqn ined December 10, 1925. serial No. 74,575.

` This invention relates `to improvements in engineers protractors, and more particularlyv to improvements in the engineers pro- `tractor forming the subject-matter of my `coper'iding application, tiled May 16, 1925,

serial-ly numberedBOO, and allowed Febklo ruary 23 *1927, and embodying a base, a limb adjustably connected to the base, and means which, while permitting the tree adjustment ,ot the limb, is adapted to hold it against jcasual movement with respectrto the base.v

The present invention has tor one ot its.

. objects therk provision otnov'el and simple means through the medium of which the limb may be 'locked or positively'secured 'against movement with resp-ect tothe base and `which shall" be adapted to be readily i i operated to either lock the limb to the base engineers protractor constructed in accord-v ance with the present invention,

Figure2 isa detail sectional view taken on the plane indicated by the yline 2+-2 of Figure 1,

Figure l3 is a detail sectional view taken jonk the plane indicated by the line 3 3 of `{Figure 1, and

Figure 4 is a similar view taken on-the ,plane indicated bythe line 4-4 of Figure 1.

' Corresponding and like parts are referred 4 to in the following description,V and desig nated in the severalviews of the accompanying drawing, by similar reference characn ters.

The protractor comprises-a base 1 having i langularly vrelated straight edges 2 and 3 and ,providedV with Vminute ygraduations 4.

The base 1 isprovided -withanfarcua-te seat 5 for-the arcuate edge 6 ot theflimb 7 which is preferably of semi-circular formation.

The base 1 andv limb` 7 are connected to permit the latter to be adjusted with respect tothe former, and thisconnection is established by means'y of a riby y8v which projects from the seat 5 and' tits in' afgroove 9irr 'ff 7 thearcuate edge 6 of the limb The limb 7 is 4provided :with degree graduations 11.-

The rib 8 is provided in itslateral sides'` with grooves 8L for the receptionot projections 9 extending inwardly from the side walls of the groove 9. plungers 12 carried by the base 1 and contacting with the limb 7, are adapted, while permitting the free adjustment of the limb,

Vto hold it against casual movement.

r The structure as far as described is embodied 'in my copending application.` kIn accordance ywith the present. invention`,-a.

friction block 13 carried by the rib 8 and an j Spring pressed contacting withthe projections 9a of the limb 7, isemployed t'or the purpose of lock- 'ing or positively securing the limb against .A vrod 14 extending diagonally through the movement with respect toy the base r1;

base l and lconnected at its` inner end to the friction block 13, and a nut 15 threaded Y on the outer end of the rod and contacting Vwith the base, constitutefmeans by whichv vthe friction blockmay -be adjusted to lock or-release the limb 7. The lower outer corner ot the basel iscut away as shown at v16, and it is against the inclinedzsurface thus provided that the nut 15 rests.` Further-v more, the cuttingaway of this corner of the base 1 permits the nut 15 to be confined wholly within the plane of the ibase.

' The present invention contemplates mount-ing a rule 17 on the` limb 7, and the rule is slidably connected to the straightedge-of the limb by a dove-tail rib 18 formed on the rule and/fitting in a similar groove 19 formed in said edge.

From the foregoing description, taken in connection with the accompanying drawing,` v

it will be understood that the limb 7 may bereadily adjusted vwith respect tothe base 1,'that the rule 17 maybe readily adjusted 1 100 withV respect to the limbr7 and base 1, and that the limb 7 and-rule 17 may be -readily lockedn iii-adjusted positionwith respect to the base 1. To lock the limb 7 to the base 1 itis `only necessary toturn the nut 15 onto the rod 14, and to release the limb it is only necessary to turn the nut 15 on the rod 1 4 in the reverse direction.

Ity sliouldbe understood `that tliefdrawing l is merely illustra-tive' and does not ,pretendA e H to give exact proportions.. Furthermore, the

said drawing ',isillustrat-ive of a preierredV construction, it being. my 'expectationl that liinb provided with an arcuate groove rceeiving the rib and having projections on i 1 Side walls enteringr the grooves ot' the ril), I a friction block niovably carried by the rili and contacting with the projection;7 :i rod connected to the iriction block and Slidahl)Y mounted in the opening ot' the hase, :nifl :i

nut threaded on the rod and contacting` with the inclined surface ot' the base.

In testimony whereof l allix my signature.

DAVID CABRERA LOPEZ. 

